Intercommunication system



J. KIRCH INTERCOMMUNICANON SYSTEM Dec. 26, 1939.

Filed March 3l, 1938 m m @pt m W m .o

Patented Dec. 26, 1939 UNITED l STATES INTERCOMMUNICATION SYSTEM JosefKirch, Berlin, Germany, assignor to Mix & Genest Aktiengesellschaft,Berlin-Schoneberg,

Germany, a company Application March 31, In Germany 6 Claims.

The invention relates to intercommunication systems, and moreparticularly to party-line systems for securing selective calls betweenthe various branch stations thereof.

Arrangements of the above identified type are known which employ codecombinations built up by a plurality of individual signals of selectableduration so as to secure a large number of different call combinations,but the utilization of such call signals, which may be Morse signals,involves certain difflculties since, in cases that simple audible signalreproduction is employed, all other stations which are associated withthe party-line common thereto will be inuenced by a code combinationintended to call one particular station only. Such arrangementsintroduce inadequate operation and it is therefore desirable to provideone or more or `even all branch stations of a party-line with deviceswhich are adapted to perform automatic utilization of incoming callsignals, that is to say an automatic call discrimination.

The present invention has for its object to provide a simple andreliably operating arrangement for automatic call discrimination. Thisis achieved according to the invention in such manner that each signalelement of a Morse code transmitted over a party-line is adapted todisplace in response to the alternating current periodicity a particularsetting member appropriate to the ordinal number of the signal element,so as to actuate that call indicating means, the entire setting membersof which have been properly set when all signal elements have beenreceived.

Call discriminators or eliminators of the above mentioned type may beemployed eitherin all `branch stations or in certain branch stations ofthe party-line, in an exchange located at the end thereof, for example;Such stations will be effectively called merely if the code combinationallotted to this station has been accordingly received.

The invention will be more readily understood from the followingdescription taken in conjunction with the accompanying drawing, inwhich:

Fig. 1 illustrates the wiring diagram of a call discriminator in whicheach code element is adapted to operate a particular setting member,while Fig. 2 shows a modification over the arrangement of Fig. 1 inwhich all setting members are operated by a drive arrangement commonthereto.

Both embodiments hereinafter described and illustrated present the samefeature that the rate of displacement of the various setting mem- 1938,Serial No. 199,109 April 3, l1937 bers substantially depends upon thenumber of impulses which arrive over the party-line, while, inappropriate limits being independent of the impulse duration, that is tosay, of the impulse transmission speed. This is of particular importancein systems where the call signals are manually produced by the agency ofa magneto generator in the calling position. It is therefore irrelevantwhether the magneto generator is actuated rapidly or slowly in thesystems above referred to, whereas the number of pulses, i. e., thenumber of magneto generator revolutions is decisive for the operation.For example, assuming a dash-dot Morse code, the dot maybe produced byone, the dash by three revolutions of 15 the magneto generator. Sinceone revolution generally corresponds to six cycles or impulses, sixthereof are produced for a dot and eighteen for a dash.

Referring rst to Fig. l, there is shown a partyline L. The branchstation illustrated in this gure comprises a call discriminator havingan alternating current relay W and stepping mechanisms A, B, etc. Therelay W responses to each alternating current cycle transmitted over theparty-line L and may, for instance, be an alarm ringer, the armature ofwhich is provided with a control contact w. The stepping mechanisms A,B, etc., are preferably designed as telephone relays, the armatures ofwhich are equipped with a driving pawl adapted to engage a ratchetwheel. The stepping mechanism A is adapted toI receive the iirst signalelement arriving over the partyline, the second s.gnal element beingadapted to influence the stepping mechanism B and so forth. In casesthat the party-line system employs Morse code signalcomprising threesignal elements as a maximum such as etc., an entire number of threestepping mechanisms is required. Each stepping mechanism moves a camdiscy Sa, Sb, etc. The contacts Ica, Ich, etc., actuated by the camdiscs are interconnected in series relation so that the call indicatingrelay P will be operated in that branch station only, the codecombination of 45 which corresponds to the Morse code transmitted overthe line. This call indicating device vis a slow-to-operate relay whichis allowed to attract merely in vsuch cases that the last cam disc hasben arrested Von the contact allotted thereto. 50 However, this timingofthe relay prevents its attraction if the contact has been transientlyactuated, that is to say when the cam disc is moved beyond the position'in which the contact is closed. It is thus possible by the 'provision of55 a sumcient delay with respect to the operation of this relay to allotto the individual stations Morse signal combinations composed of adifferent number of signal elements. In other words, various stationsmay be called by three, and other stations by two individual signals,for example. If the codes and are simultaneously utilized in the system,the relay P is not rendered effective immediately after the receipt ofthe code on the contrary a certain time interval elapses before theoperation of this relay so as to permit the energizing circuit for therelay P of the station having the call cornbination to be dulyinterrupted prior to the receipt of-an eventually arriving third elementwhich in the present case was assumed to be a dash.

It may be pointed out in this connection that dashes of particularlengths may be employed as call signals in addition to the normal dashesand dots. Such dashes of longer duration may, for example, be producedby ten revolutions of the magneto generator and utilized for collectiveor accident calls, in which case the cam discs in addition to the camfor individual calls must be provided with a second cam for thecollective call, these additional cams being identically positioned inall stations. The angular displacement of the stepping mechanismconcerned, e. g. the stepping mechanism A in the case underconsideration, is thus particularly large in connection with theaforementioned type of calls.

Again referring to Fig. l, it may be assumed that the stationillustrated therein may be called by a code combination, the firstsignal of which is a dot and the second signal of which is a dash. Theoperation in this station is in this case as follows:

The calling station transmits by one single revolution of the magnetogenerator the rst calling signal, i. e. the dot, which comprises siXimpulses whioh are received by the relay W in the station shown. Thecontact w thus oscillates to and fro six times. The :first impulseenergizes the relay X over the contact sa and the resistance Wi, wherebythe reverted contact :nl of the relay X transfers the received impulsesto the stepping mechanism A over the contact w, the relay X and thecontact .'cl. The contact .r2 disconnects the relay Y from the contactof relay W. The stepping mechanism A now advances its pertaining camdisc step by step. As Soon as the cam disc has been brought out from itsnormal position, a contact sa is reverted in any known manner (notshown) with the result that the original energizing circuit for therelay X is interrupted, while on the other hand battery current throughthe resistance Wi is preparatorily applied to the relay Y. The steppingmechanism A advances its cam disc Sa by a given angle of rotation underthe influence of the received current impulses and this advancementcorresponds to six steps, so that the cam na at the conclusion of thetrain of impulses closes the contact ka. Since the relay X is aslow-to-release element, this relay remains operated during the receivedimpulse train over its contact xl. At the end of the impulse trainreferred to, the relay X releases whereby its contact all is restored tonormal. On receipt of the second train of impulses which as abovementioned comprises 3 6=18 pulses, the relay Y is energized over thefollowing circuit: ground, contact w, contact m2, relay Y, cam contactsb, cam contact sa, resistance Wi, battery, ground. This relay tilts itsy-contacts so as to apply the stepping mechanism B under the inuence ofcontact w. The cam disc Sb is thereby displaced by an angular rotationwhich corresponds to 18 steps, so that the contact kb is actuated afteriinished train of impulses as will be obvious from the illustration. Inthe same moment in which the cam disc Sb has been moved out from itshome position, the cam contact sb is tilted in a similar manner asheretofore described in connection with the cam contact sa, whereby afurther stepping mechanism will be prepared for the reception of a thirdtrain of impulses. In cases that the total number of Morse or codesignals correspond to the code combination allotted to the station underconsideration, the relay P operates after the elapse of a given periodof time over the serially connected cam contacts ka, ich, etc. Onattraction the relay P tilts its contact pl thus establishing a circuitfor relay R which is caused to operate. The contact of this relayestablishes a holding circuit for this relay, while contact r2 causesthe call indicating lamp AL to be lightened. The call is then answeredto when the operator at this station inserts a plug (not shown) in thejack KI, whereby a conversation may be entered. The insertion of theplug in the jack Kl interrupts the holding circuit for relay R withresult that its contact T2 restores to normal whereby the callindicating lamp AL eXtinguishes. I

It will readily be observed from the illustration that a thermo-relay THis heated from that Very moment in which the stepping mechanism A wasmoved out from its home position. The energizing circuit for thisthermo-relay is traced as follows: ground, battery, resistance Wi camcontact sa, thermo-relay TH, contact mi, contact 1'3, thermo-relaycontact th, ground. The relay IVI is unable to attract since beingshort-circuited over the contacts mi r3 and th. However, theenergization of relay R causes this shortcircuit to be removed atcontact r3 so that the relay M is energized whereby its Contact mlestablishes a short-circuit across the relay TH and at the same time anown holding circuit. The contacts m2, m3, etc. of the relay M aresimultaneously closed so as to cause the stepping mechanisms A, B, etc.,to be released one after another in a succession which is opposite tothat of their energizations. The homing circuit for the steppingmechanism B is thus traced as follows: ground, battery, steppingmechanism B, contact yi, self-interrupter contact b, contact m3, dottedconnection, cam contact sb, contact mi, relay M, ground. The cam contactsb is restored to normal as soon as the stepping mechanism B has beenhorned, so that also the stepping mech-v anism A will be released over:ground, battery, stepping mechanism A, contact mi, self-interruptercontact a., contact m2, cam contact sb, contact mi, relay M, ground.When the last stepping mechanism has been restored to normal, the canicontact sa is reverted so that the relay M becomes de-energized,whereupon all switching means of the called branch station are restored.

The relay R of al1 other stations for which the transmitted codecombination was not intended does not operate, so that the thermorelayTl-I of these stations attracts after the elapse of a given period so asto permit the relay M to be energized by removing, at contact th, theshort-circuit across this relay. The stepping mechanisms of theaforementioned branch stations are then again released in the samemanner as heretofore described in connection *with the actually calledstation.

The arrangement shown in Fig. 2 diers from that according to Fig. 1,since all setting members, that is to say the cam discs sa, sb, etc.,are moved in response to an electric drive WW common thereto. Thiselectric drive system is an ordinary alternating current steppingmechanism as usually employed in connection with party-line systems. Thecam discs are loosely provided on the shaft of this mechanism and mustbe clutched to the shaft by the agency of speciiic clutching relays A,B, etc. These clutching relays are controlled by means of a relay WRwhich in the arrangement according to Fig. 2 is connected in series withthe electric drive WW to the party-line L. Itis obvious that these twomeans may be connected in parallel with one another. The relay WR isadapted to response to complete alternating current trains of impulsesonly and not to release under the iniluence of the individualalternating current cycles. It is thus possible to employ a phase relayin the position of the element WR.

On receipt of the first individual signal, a dot, for instance, therelay WR responses and its contact wr causes the clutching relay A to beenergized so as to engage the first cam disc Sa with the shaft of theelectric drive system. Under the inuence of the individual elements ofthe first signal transmitted, the cam disc Sa is advanced into theangular position which corresponds to the length of the alternatingcurrent transmission. The contact a is thereby closed but the relay X isnot energized prior to the end of the alternating train of impulsessince previously short-circuited by the contact wr. When operated, therelay X establishes an own holding circuit at contact :122, whereby therelay A simultaneously releases by virtue of the shortcircuitestablished thereacross. The cam disc Sa is then disengaged from theshaft of the drive mechanism and arrested in the position thus reached.The relay X preparatorily at contact connects the contact chain throughto the second clutching relay B.

Consequently, on receipt of the second train of impulses, that is tosay, the second train of alternating cycles, also the relay B isenergized over contact wr with the result that the cam disc Sb isclutched to the shaft of the driving mechanism under the influence ofthe electric drive system WW and thus advanced into the desiredposition. At the end of the second train of impulses also relay Breleases since being short-circuited at Contact y2 of relay Y which isnow attracted. The contact yl connects the contact chain through tofurther devices if such have been provided.

All cam discs Sa, Sb; etc., are thus set one after the other in allstations, while being set as heretofore described in connection with thearrangement of Fig. l on that station to which the transmitted codecombination is allotted. 'Ihe relay P is then energized over the seriesconnected contacts of the cam discs Sa, Sb, etc. On operation, itscontact pl causes the energization of the relay R, the contact r2 ofwhich establishes the circuit for the call indicating lamp AL which islightened similarly as described in conjunction with the firstembodiment. The call is thus answered to exactly in the same manner asdescribed in connection with Fig. 1, The embodiment illustrated in Fig.2 also employs a thermo-relay TH which is heated over contact x3`immediately after the commencement of the alternating currenttransmission. After the operation of this thermo-relay, or, if theactually called station is concerned, after the operation of relayR,also relay M is energized so as to release relay X at contact m2 andrelay Y at contact m3 and to effect homing of the cam discs over afurther contact (not shown). This may, for instance, be effected by theagency of a retracting spring which is relieved by the relay M. It isalso possible to connect the electric system WW in a self-interruptingcircuit, for instance, so that the shaft common thereto is againstarted. The cam discs may thus be restored to normal by clutching themseveral times tothe shaft common thereto.

It is also possible to substitute the electric drive WW by a machinedrive arrangement responsive to the current flowing over the line.Moreover, the cam discs may be replaced by contact arms or the like.Finally, the release. or homing of the circuit elements thus set may beeffected according to other principles than shown in the Figs. 1 and 2.For instance, a particular release key may be employed, while therelease of the called station may be effected by any type of switchingmeans instead of relay R operated in response to an incoming call, suchswitching means being actuated on answering to the call, that is to say,when the operator inserts the plug into the answering jack, for example.

What is claimed is:

1. A party-line system having several branch stations, a party-linecommon thereto, and means for generating alternating current Morse'codesignal consisting of a plurality of signal elements each of which beingcomposed of any desired number of alternating current cycles, eachbranch station comprising means responsive to alternating currentcycles, means responsive to said signal elements and controlled by saidalternating current cycle responsive means, a plurality of membersindividually allotted to the corresponding signal element of appropriateordinal number and adapted to be moved into any of a plurality ofpositions by said signal element responsive means under the influence ofthe number of alternating current cycles transmitted, means forsuccessively distributing eachof said signal elements to itsappertaining member, call indicating means operable in dependency on theposition of said members after the receipt of all signal elements of aMorse code signal, a timing device adapted to restore all means tonormal after the elapse of a given interval, and means for automaticallyr-eleasing the called station on answering to a call.

2. A party-line system as defined in claim 1, in which said alternatingcurrent cycle responsive means is a line relay common to all signalelement responsive means.

3. A party-line system as defined in claim 1, in which said alternatingcurrent cycle responsive means is a polarized alternating current alarmmechanism the armature of which is adapted to operate control contacts.

4. A party-line system as defined in claim 1, in which said distributingmeans are relays adapted to be successively energized during the stationcomprising stepping mechanisms individually allotted to thecorresponding signal element of appropriate ordinal number, a pluralityof members individually allotted to the corresponding Stepping mechanismand adapted to be moved thereby into any of a plurality of positionsunder the iniiuence of the number of alternating current cyclestransmitted, means for successively distributing each of said signalelements to its appertaining stepping mechanism, call indicating meansoperable in dependency on the position of said members after the receiptof all signal elements of a Morse `code signal, a timing device adaptedto restore all means to normal after the elapse of a given interval, andmeans f/or automatically releasing the called station on answering to acall.

6. A party-line system having several branch stations, a partyelinecommon thereto, and means for generating alternating current Morse codesignals consisting oi a plurality of signal elements each being composedof any desired number of alternating current cycles, each branch stationcomprising means responsive to said signal elements, an electric driveenergized by alternating current cycles transmitted over saidparty-line, a plurality of members individually allotted to thecorresponding signal element of appropriate ordinal number, clutchingmeans responsive to said signal elements and adapted to successivelyclutch said members to said drive so as to move said members into any ofa plurality of positions under the influence of the signal elementsreceived, means for successively distributing the signal elements to theappertaining clutching means, call indicating means operable independency on the position of said members after the receipt of allsignal elements or a Morse code signal, a timing device adapted torestore all means to normal after the elapse of a given interval, andmeans for automatically releasing the called station on answering to acall.

JOSEF KIRCH.

